SOLUTION: Sam has scored a 70%, 85%, 94%, and an unknown score on his fourth test. Find an expression that explains what Sam has to get on his 5th test to have a test average of 90%. Thank

Algebra ->  Average -> SOLUTION: Sam has scored a 70%, 85%, 94%, and an unknown score on his fourth test. Find an expression that explains what Sam has to get on his 5th test to have a test average of 90%. Thank       Log On


   



Question 990785: Sam has scored a 70%, 85%, 94%, and an unknown score on his fourth test. Find an expression that explains what Sam has to get on his 5th test to have a test average of 90%.
Thank you.

Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
.
The sum of 5 grades to average 90 is (5)(90)=450
Let x=4th score and y=5th score
450-70-85-94-x-y=0
201-x=y
.
Sam must get a score of (201-his fourth score)
on his fifth test to average 90.
(He must average more than 100% on tests 4 and 5).
.